How to fireblock framing

Wildie is correct. Although it is a structure protection issue more than fireblocking, any accessible area underneath a stair in an otherwise finished area is required to be sheetrocked. If the area under the stairs is not accessible, not rock is required by the code. In a fire it is good for the stairs to remain intact as long as possible.

How to fireblock framing

That makes me hungry for smores.

I figured that the fireblocking foam would perform a little better. There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.

How to fireblock framing

Since this thread is evolving into all sorts of fire protection related issues in single family homes (draftstopping, sheetrock, etc), I'm going to go ahead and cover other fire-protection topics people may encounter during a remodel or addition.

How to fireblock framing

Why use sheetrock in a home as opposed to another material? I'll describe how it works, and why it has a real advantage over other matierials in a fire.

Sheetrock is generally noncombustible. But that isn't all of what makes it good for preventing fire from getting from your garage, for instance, into your home. Sheetrock's biggest function in a fire is to resist the transfer of heat to the framing members that it protects.

If you ever lift sheetrock, you know it is heavy. A lot of that weight is derived from the gypsum's moisture content. It contains about 21% water by weight. Amazing, huh?

When heated by a fire, the water is slowly released in the form of steam, which serves as a thermal barrier to retard the transfer of heat. This process is called calcination. The Gypsum Association's manual gives a good analogy to help understand this. If you hold a block of ice in your hand, and use a blowtorch on the other side, your hand doesn't feel any heat. The calcination process is finished when the gypsum is devoid of moisture. Even when the moisture is gone, the sheetrock's mass and noncombustible properties continue to protect the structure from direct ignition from flames for a limited period of time as heat transfer through the gypsum increases. After enough heat exposure and heat increase, the wood framing members ignite and/or the steel structural members begin to soften and lose strength.

How to fireblock framing

The only room you're absolutely required to sheetrock in your house is the garage. That will change in future code cycles, but we'll deal with current code here.

Lots of house fires originate in the garage. Fuel vapors, cars, lawnmowers, and other flammables are often stored in the garage. The code requires that the residence and its attic area be protected from the garage by 1/2" sheetrock on the walls. If there is habitable space above the garage, the ceiling must be rocked with 5/8" type X. Any structural elements (steel or wood posts, steel or wood beams, exterior walls, etc) that support the structure above must also be protected by 1/2" rock.

Openings from the garage into the protected spaces of the residence must be equipped with 1-3/8" thick solid wood or honeycombed steel doors, or 20 minute rated fire doors. Most inspectors interpret this to also include attic access holes or drop down attic stairs in the garage....Neither are a good idea in a garage space.

Ducts that pass through the garage must be 26 gauge. HVAC openings are not permitted in the garage. Although the code makes no allowance for them, I'll approve HVAC vents in the garage if UL listed 1 hour fire dampers are used and properly installed. Under no circumstance would I allow a return air vent opening in a garage.

Installations of a number of things can compromise the integrity of the fire membrane that is required in the garage, and would easily allow passage of flame or heat in a garage fire. Electrical, for one. The building code prohibits installation of electrical boxes in fire membranes is the hole they create exceeds 16 square inches (2-gang box). Electrical panels recessed in the garage sheetrock violate this code, as do can lights, as do mudrings that are commonly used for garage openers, speakers, alarms, and central vac's. What's the point of going to the trouble of installing 5/8" type X rock in the ceiling and then punching ten 6" holes in it for can lights that won't even slow a fire down?

How to fireblock framing

Quote:

Originally Posted by thekctermite

That makes me hungry for smores.

I figured that the fireblocking foam would perform a little better. There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.

I'm really not too surprised. Great Stuff Fireblock meets UL1715, which is a flammability standard. Nowhere do they claim that it is fireproof. In order to work, it only needs to burn away at a rate slower than other materials around it. In other words, if you closed an opening through a wood framed wall with foam and subjected it to a fire, the wooden part of the wall would burn away at the same rate or faster than the foam. Therefore the foam did it's job, even though it too would burn away. Keeping in mind that it only has to perform long enough to pass the test. Nowhere have I come across any UL rated firestop systems using Great Stuff foam. There are about 30 for Hilti fire foam and a number for 3M, both of which are silicone based rather than urethane. Just as info, if you ever come across Great Stuff in a wall or floor where a fire rating is required by code, ask to see a copy of the UL firestop assembly system showing that it was tested. If it can't be produced, it should not pass inspection.

How to fireblock framing

Quote:

Originally Posted by Maintenance 6

Nowhere have I come across any UL rated firestop systems using Great Stuff foam. There are about 30 for Hilti fire foam and a number for 3M, both of which are silicone based rather than urethane. Just as info, if you ever come across Great Stuff in a wall or floor where a fire rating is required by code, ask to see a copy of the UL firestop assembly system showing that it was tested. If it can't be produced, it should not pass inspection.

Just so everyone understands, fireSTOPPING is very rarely encountered in single family residences. It is common in townhomes, apartments, and commercial structures. As M6 stated, I've never seen a UL firestop listing that allows fire foam. Typically firestopping products such as intumescent caulk, collars, putty pads, etc are used for firestopping.

FireBLOCKING on the other hand is a perfect application for this type of foam, and that is exactly what it is listed for. Follow the manufacturer's guidelines regarding the maximum gap it can fill though.

How to fireblock framing

Quote:

Originally Posted by thekctermite

Just so everyone understands, fireSTOPPING is very rarely encountered in single family residences. It is common in townhomes, apartments, and commercial structures. As M6 stated, I've never seen a UL firestop listing that allows fire foam. Typically firestopping products such as intumescent caulk, collars, putty pads, etc are used for firestopping.

FireBLOCKING on the other hand is a perfect application for this type of foam, and that is exactly what it is listed for. Follow the manufacturer's guidelines regarding the maximum gap it can fill though.

Just to clarify. I'm not bashing Great Stuff fire blocking foam. It does everything it's supposed to do and is a good product for residential use. The point I was trying to make is that firestopping is a complex science and just because the material burns over a campfire doesn't mean that it won't do it's job in a real fire situation. And that anyone with a need for a true rated firestop system should look to other products (although not likely in a DIY setting). By the way. Good thread Termite. Excellent topic and illustrations. Probably one of the most misunderstood components of construction, by builders, homeowners and inspectors.

How to fireblock framing

By the way. Good thread Termite. Excellent topic and illustrations. Probably one of the most misunderstood components of construction, by builders, homeowners and inspectors.

Thanks Maintenance 6. I agree, fireblocking and firestopping are more often than not completely misunderstood by the people installing them.

More than once I've borrowed a plumber's turbotorch to heat up some intumescent firecaulk on a jobsite so the guy that is installing it (and has been installing it for years) can actually see what it does in a fire. It cracks me up to watch the amazed look on their faces as the caulk intumesces like crazy. Once someone gains an understanding of how the system they're installing performs in a fire, they can do a better job of installing it.

How to fireblock framing

I am currently certified by 3M and had the opportunity to work with a 3M field rep several years ago to help develop some firestop systems that are now UL listed. A lot of money is invested in testing the systems and procedures that you illustrated, to prove that they will do what they are supposed to under actual conditions. I had the priveledge to witness a couple of UL tests and they are brutal. Everything tested must pass 100% in order to become accredited. Fireblocking and firestopping procedures aren't just a way to make more work for a framer or remodeller (or a DIYer). They are tested systems.............and they work.

How to fireblock framing

Trying to decide between steel or wood studs in basement walls. I am putting in a grid style tiled drop ceiling. Here are the questions. Does a drop ceiling count as concealed space? If so, what the best way to fireblock between metal studs? The groove in c channel of the stud makes blocks difficult to make? Or is regular blocks and firefoam the way here?

What about behind the studs? In a basement remodel the studs can never go directly against the foundation wall. One thought I had was to lag a 2x4 horizonal at ceiling height. That way I'd have a nice surface to mate my fireblocks between the studs too.

How to fireblock framing

Quote:

Originally Posted by awang13

Trying to decide between steel or wood studs in basement walls. I am putting in a grid style tiled drop ceiling. Here are the questions. Does a drop ceiling count as concealed space? If so, what the best way to fireblock between metal studs? The groove in c channel of the stud makes blocks difficult to make? Or is regular blocks and firefoam the way here?

What about behind the studs? In a basement remodel the studs can never go directly against the foundation wall. One thought I had was to lag a 2x4 horizonal at ceiling height. That way I'd have a nice surface to mate my fireblocks between the studs too.

Any comments?

As for the grid ceiling, there are a couple interpretations because the code doesn't speak to it. Personally, I require fireblocks at the ceiling line on grid ceilings because the space above the ceiling is in fact concealed space.

Blocking between metal studs is a challenge for sure. The pros make it look easy, somehow. Personally, I'd use 2x blocking and screw it in. The channels would have to be packed with fiberglass or rock wool. When using steel studs it is best to meet with your inspector ahead of time to make sure that your method will be acceptable to him/her.

Attaching a 2x4 to the wall to act as a fireblock would work ok, but if the foundation wall ever moves you'll regret doing it. Instead, I'd suggest fire foam or fiberglass (or rock wool) stuffed between the foundation wall and the back of the horizontal blocking you install at the ceiling line. Just as effective but less risk of cracking the new framed wall if the foundation moves 1/8".

Another consideration with steel studs is that they have holes in them for wiring and pipes. Those holes must be blocked off every 10' horizontally, and any penetrations of the top track must also be blocked.

How to fireblock framing

How to fireblock framing

Quote:

Originally Posted by Kermie

Now to the question: I have framed a wall similar to the above picture in front of the EPS Foamboard with a 1" gap.
So basically at the top plate and vertically needs fireblocking? I will attach 1/2" drywall from the top plate to the sill fro the entire wall but how do I fireblock horizontally without disrupting the insulation/vapor barrier? (note: The framed wall will be completely stuffed with unfaced mineral wool for sound as well)

The foamboard complicates things, so I definately advise that you speak with your building inspector regarding how they want it fireblocked.

In my opinion, the installation of mineral wool in the entire cavity will create a very effective fireblock. Provided all voids are filled, I wouldn't require anything else.